/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Reflection;

namespace Spring.Core;

/// <summary>
/// Criteria that is satisfied if the number of generic arguments to a given
/// <see cref="System.Reflection.MethodBase"/> matches an arbitrary number.
/// </summary>
/// <remarks>
/// <p>
/// This class supports checking the generic arguments count of both
/// generic methods and constructors.
/// </p>
/// </remarks>
/// <author>Bruno Baia</author>
public class MethodGenericArgumentsCountCriteria : ICriteria
{
    /// <summary>
    /// Creates a new instance of the
    /// <see cref="MethodGenericArgumentsCountCriteria"/> class.
    /// </summary>
    /// <remarks>
    /// <p>
    /// This constructor sets the
    /// <see cref="MethodGenericArgumentsCountCriteria.ExpectedGenericArgumentCount"/>
    /// property to zero (0).
    /// </p>
    /// </remarks>
    public MethodGenericArgumentsCountCriteria() : this(0)
    {
    }

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="MethodGenericArgumentsCountCriteria"/> class.
    /// </summary>
    /// <param name="expectedGenericArgumentCount">
    /// The number of generic arguments that a <see cref="System.Reflection.MethodInfo"/>
    /// must have to satisfy this criteria.
    /// </param>
    /// <exception cref="System.ArgumentException">
    /// If the supplied <paramref name="expectedGenericArgumentCount"/> is less
    /// than zero.
    /// </exception>
    public MethodGenericArgumentsCountCriteria(int expectedGenericArgumentCount)
    {
        ExpectedGenericArgumentCount = expectedGenericArgumentCount;
    }

    /// <summary>
    /// The number of generic arguments that a <see cref="System.Reflection.MethodInfo"/>
    /// must have to satisfy this criteria.
    /// </summary>
    /// <exception cref="System.ArgumentException">
    /// If the supplied value is less than zero.
    /// </exception>
    public int ExpectedGenericArgumentCount
    {
        get { return _count; }
        set
        {
            if (value < 0)
            {
                throw new ArgumentOutOfRangeException(
                    "value", value, "Cannot specify a generic argument count of less than zero.");
            }

            _count = value;
        }
    }

    /// <summary>
    /// Does the supplied <paramref name="datum"/> satisfy the criteria encapsulated by
    /// this instance?
    /// </summary>
    /// <param name="datum">The datum to be checked by this criteria instance.</param>
    /// <returns>
    /// True if the supplied <paramref name="datum"/> satisfies the criteria encapsulated
    /// by this instance; false if not or the supplied <paramref name="datum"/> is null.
    /// </returns>
    public bool IsSatisfied(object datum)
    {
        bool satisfied = false;
        MethodBase method = datum as MethodBase;
        if (method != null)
        {
            satisfied = method.GetGenericArguments().Length == ExpectedGenericArgumentCount;
        }

        return satisfied;
    }

    private int _count;
}